How to return bytes to C#/.net from C? -

here's c function:

 dll_public void alve_ripemd320__finish(void* instance, uint32_t* out_hash)  {       ...      (uint32_t i=0, i_end=10; i<i_end; i++)      {          out_hash[i] = h[i];       }  } 

and here how i'm calling c#:

 [dllimport(platformconstants.dllname)]  static extern void alve_ripemd320__finish (intptr instance_space, ref byte[] hash);   ...   public byte[] finish()  {      byte[] result = new byte[40];      alve_ripemd320__finish (c_instance, ref result);      return result;  } 

and produces ugly segfault, goes away if comment c-code above writes out_hash.... question is, correct way of passing buffer of bytes using pinvoke?

your c api writing unsigned integers. typically expect mapped as:

[dllimport(platformconstants.dllname, callingconvention=callingconvention.cdecl)] static extern void alve_ripemd320__finish(intptr instance_space, uint[] hash);  public uint[] finish() {    uint[] result = new uint[10];    alve_ripemd320__finish (c_instance, ref result);    return result; } 

there 3 main changes here:

1. i switched calling convention cdecl. standard c++ compiler (unless you're explicitly switching stdcall in dll_public).
2. i changed match c api, uses 32 bit unsigned integers instead of bytes. should able switch byte[] if choose, however.
3. you shouldn't need pass ref. typically equivelent of c api accepting uint32_t** out_hash, not uint32_t* out_hash, should map array directly.